I have to say I've had really good luck with my Plus. Even before the update, I only had a handful of carts (out of 100 or so) that gave me any grief.'
With cleaning and a firmware update, the only cart that gives me a problem now is Tac-Scan: it runs, but doesn't recognize paddles.
I understand that the 'experimental' update fixes this but I haven't tried it yet; I figured I might as well wait for the next update.